Scalding injuries caused by unexpected fluctuations in water temperature are a serious hazard, especially in households with small children. Most modern single-handle shower valves have an an anti-scald feature that allows you to set a safe limit on the temperature of the water. Temperature control valves, also known as tempering, mixing or thermostatic valves, are unfortunately much less common on residential kitchen and bathroom faucets. Add-on tempering valves are available from various manufacturers, and are simple to plumb into an under-the-sink application.

1

Turn off the hot and cold water supplies to the faucet. Open the faucet to reduce pressure in the lines. Place a bucket or old towel underneath the supply lines feeding the faucet to catch any leaks during installation.

2

Disconnect the hot and cold water supply lines from the shut-off valves using an adjustable wrench. Leave the other ends of the lines attached to the faucet inlets.

3

Attach new flexible supply lines to the hot and cold inlets of the tempering valve. Tighten the connections with an adjustable wrench. Hold the valve so the hot and cold inlets point downward with the hot inlet on the left side. Connect the free end of the new hot water supply line coming from the tempering valve to the hot water shut-off valve and tighten securely. Connect the new cold water supply line to the cold water shut-off valve and tighten securely.

4

Connect the flexible supply line coming from the hot water side of the faucet to the tempering valve hot water outlet and tighten securely. Connect the flexible supply line from the cold water side of the faucet to the tempering valve's cold water inlet and tighten securely. Position the tempering valve so its adjustment knob is easily accessible.

5

Turn on the hot and cold water supplies to the faucet and check for leaks. Open the hot side of the faucet or adjust a single handle model to the full hot position. Run the hot water and check the temperature with a thermometer. Adjust the temperature to a safe level following the manufacturer's instructions for the tempering valve.

Things You Will Need

Bucket or old towel

Adjustable wrench

2 reinforced flexible water supply lines

Thermometer

Tips

For residential under-the-sink applications, look for a four-port tempering valve that features both hot and cold water outlets. Three-port valves are generally used in either commercial applications or designed to be installed at the hot water heater.

Tempering valves are available in a variety of connection types, including threaded, soldered, compression and plastic pipe. Examine the plumbing connections underneath your sink to determine which type will best fit your application.

Warning

Tempering valves must be set to a safe level before use. Many valve manufacturers recommend a maximum temperature of 110 degrees Fahrenheit.

About the Author

Steve Hamilton has been writing professionally since 1983. His credits include novels under the Dell imprint and for Harlequin Worldwide. A remodeling and repair specialist with over 20 years experience, he is also a Certified Pool Operator and holds an EPA Universal refrigerant certification.